title: Non-ionic, thermo-responsive DEA/DMA nanogels: synthesis, characterization, and use for DNA separations by microchip electrophoresis.
abstract: Thermo-responsive polymer "nanogels" (crosslinked hydrogel particles with sub-100 nm diameters) are intriguing for many potential applications in biotechnology and medicine. There have been relatively few reports of electrostatically neutral, thermosensitive nanogels comprising a high fraction of hydrophilic co-monomer. Here we demonstrate the syntheses and characterization of novel, non-ionic nanogels based on random N,N-diethylacrylamide (DEA)/N,N-dimethylacrylamide (DMA) copolymers, made by free-radical, surfactant-free dispersion polymerization. The volume-phase transition temperatures of these DEA/DMA nanogels are strongly affected by co-monomer composition, providing a way to "tune" the phase transition temperature of these non-ionic nanogels. While DEA nanogels (comprising no DMA) can be obtained at 70 °C by standard emulsion precipitation, DEA/DMA random co-polymer nanogels can be obtained only in a particular range of temperatures, above the initial phase transition temperature and below the critical precipitation temperature of the DEA/DMA copolymer, controlled by co-monomer composition. Increasing percentages of DMA in the nanogels raises the phase transition temperature, and attenuates and broadens it as well. We find that concentrated DEA/DMA nanogel dispersions are optically clear at room temperature. This good optical clarity was exploited for their use in a novel DNA sieving matrix for microfluidic chip electrophoresis. An ultrafast, high-efficiency dsDNA separation was achieved in less than 120 s for dsDNA ranging from 75 bp to 15,000 bp.
authors.affiliation: Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA. xhlu2002@gmail.com
authors.forename: Xihua
authors.initials: X
authors.lastname: Lu
authors.forename: Mingyun
authors.initials: M
authors.lastname: Sun
authors.forename: Annelise E
authors.initials: AE
authors.lastname: Barron
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D004247:DNA / Q000032:analysis*; D046209:Electrophoresis, Microchip; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D000080385:Nanogels; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry*; D011094:Polyethyleneimine / Q000138:chemical synthesis / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013696:Temperature
chemical_list: D000178:Acrylamides; D000080385:Nanogels; D011108:Polymers; C428028:poly(N,N-diethylacrylamide); C413692:polyethylene glycol polyethyleneimine nanogel; D011092:Polyethylene Glycols; D011094:Polyethyleneimine; D004247:DNA; C099046:N,N-dimethylacrylamide